Q1. A mysterious, highly contagious infection in Angola is causing fever, vomiting, cough, diarrhea, and bleeding. Viral RNA is isolated from a blood sample. What is the disease? What caused the disease?

Background

Topic: Viral Hemorrhagic Fevers

This question tests your ability to recognize the clinical presentation and epidemiology of viral hemorrhagic fevers, as well as to identify the causative agent based on symptoms and laboratory findings.

Key Terms and Concepts:

• Viral hemorrhagic fever: A group of illnesses caused by several distinct families of viruses, often characterized by fever and bleeding disorders.

• Filoviruses: Includes Ebola and Marburg viruses, which are known to cause severe hemorrhagic fevers.

• Transmission: Often through direct contact with blood or body fluids of infected individuals.

• RNA virus: The causative agent is identified as an RNA virus.

Step-by-Step Guidance

1. Review the symptoms: fever, vomiting, cough, diarrhea, and bleeding, with high contagion and rapid spread in close contacts.

2. Consider the epidemiological context: outbreak in Angola, high mortality, and rapid transmission among families.

3. Note the laboratory finding: viral RNA isolated from blood, suggesting a viral etiology.

4. Recall which viral families cause hemorrhagic fevers in Africa, especially those with RNA genomes.

5. Think about the most notorious viral hemorrhagic fevers in Africa and their causative agents.

Try solving on your own before revealing the answer!

Q2. Margaret, a pregnant woman, had a miscarriage after cleaning a kitten's litter box. Blood tests show infection with cysts from a protist parasite. What is the most likely cause of Margaret’s condition?

Background

Topic: Parasitic Infections and Zoonoses

This question tests your understanding of zoonotic diseases, especially those transmitted from cats to humans, and their impact on pregnancy.

Key Terms and Concepts:

• Protist parasite: A single-celled eukaryotic organism that can cause disease.

• Cysts: Dormant, resistant forms of some parasites that can survive in the environment.

• Zoonosis: Disease transmitted from animals to humans.

• Congenital infection: Infection acquired by the fetus during pregnancy.

Step-by-Step Guidance

1. Identify the risk factor: cleaning a cat's litter box exposes individuals to certain parasites.

2. Recall which protist parasite is commonly associated with cats and can form cysts.

3. Consider the impact of this parasite on pregnant women and the fetus.

4. Think about the name of the disease and the organism responsible.

Try solving on your own before revealing the answer!

Q3. A 4-year-old boy with cough, conjunctivitis, fever, and a spreading macular rash has red lesion-like spots inside his mouth. What are the spots? What is the disease? What caused the disease?

Background

Topic: Viral Exanthems (Rash Illnesses)

This question tests your ability to recognize classic signs of viral childhood diseases and identify their causative agents.

Key Terms and Concepts:

• Macular rash: Flat, red spots on the skin.

• Koplik's spots: Small, white lesions inside the mouth, pathognomonic for a specific viral disease.

• Measles: A highly contagious viral disease with characteristic symptoms.

• Paramyxovirus: The family of viruses that includes the measles virus.

Step-by-Step Guidance

1. List the symptoms: cough, conjunctivitis, fever, macular rash, and oral lesions.

2. Recall which childhood viral illness presents with these symptoms and oral spots.

3. Identify the name of the oral lesions that are diagnostic for this disease.

4. Determine the name of the disease and the virus responsible.

Try solving on your own before revealing the answer!

Q4. An 8-year-old boy develops a vesicular rash on his neck and stomach. Within 5 days, 73 students in his school have similar symptoms. What is the disease? What caused the disease?

Background

Topic: Viral Skin Infections

This question tests your knowledge of common childhood viral diseases that cause vesicular rashes and their modes of transmission.

Key Terms and Concepts:

• Vesicular lesions: Small, fluid-filled blisters on the skin.

• Highly contagious: Rapid spread among children in close contact.

• Varicella-zoster virus: The virus responsible for a classic childhood exanthem.

Step-by-Step Guidance

1. Note the presentation: vesicular rash, rapid spread among classmates.

2. Recall which childhood disease is characterized by vesicular lesions and is highly contagious.

3. Identify the causative virus for this disease.

Try solving on your own before revealing the answer!

Q5. A 20-year-old man has eye redness with dried mucus crust in the morning, which resolves with topical antibiotics. What is the disease? What caused the disease?

Background

Topic: Bacterial Eye Infections

This question tests your ability to recognize common bacterial infections of the eye and their typical presentations.

Key Terms and Concepts:

• Conjunctivitis: Inflammation of the conjunctiva, often called "pink eye".

• Bacterial etiology: Responds to antibiotics, often produces purulent discharge.

Step-by-Step Guidance

1. Identify the symptoms: eye redness, mucus crust, resolution with antibiotics.

2. Recall the common causes of conjunctivitis and their response to treatment.

3. Determine the most likely diagnosis and causative agent.

Try solving on your own before revealing the answer!

Q6. A day-care worker in North Dakota develops fever, rash, headache, and abdominal pain, then dies rapidly. Gram-positive diplococci are found in cerebrospinal fluid. What is the disease? What caused the disease?

Background

Topic: Bacterial Meningitis

This question tests your ability to interpret Gram stain results and clinical presentation to diagnose central nervous system infections.

Key Terms and Concepts:

• Meningitis: Inflammation of the membranes covering the brain and spinal cord.

• Gram-positive diplococci: Bacterial morphology seen in Streptococcus pneumoniae.

• Rapid progression: Suggests a severe bacterial infection.

Step-by-Step Guidance

1. Review the symptoms: fever, rash, headache, abdominal pain, rapid decline.

2. Interpret the Gram stain: Gram-positive diplococci in CSF.

3. Recall which bacteria have this morphology and cause meningitis.

4. Determine the diagnosis and causative agent.

Try solving on your own before revealing the answer!

Q7. An 8-year-old girl in Wisconsin develops chills, headache, fever, and coma after mosquito bites. CAT scan shows brain swelling. Antibiotics are ineffective. What is the disease? What caused the disease?

Background

Topic: Arboviral Encephalitis

This question tests your knowledge of vector-borne viral infections affecting the central nervous system.

Key Terms and Concepts:

• Encephalitis: Inflammation of the brain, often viral in origin.

• Arbovirus: Arthropod-borne virus, transmitted by mosquitoes.

• Antibiotics ineffective: Suggests a viral, not bacterial, cause.

Step-by-Step Guidance

1. Note the exposure: mosquito bites, outdoor activity.

2. Consider the symptoms: fever, headache, coma, brain swelling.

3. Recall which arboviruses are common in the U.S. and cause encephalitis.

4. Think about why antibiotics would not help in this case.

Try solving on your own before revealing the answer!

Q8. After eating canned chili, two children develop cranial nerve paralysis and descending paralysis. Bacteria isolated from the chili only grow anaerobically. What is the disease? What caused the disease?

Background

Topic: Foodborne Bacterial Intoxications

This question tests your understanding of neurotoxic foodborne illnesses and the characteristics of anaerobic bacteria.

Key Terms and Concepts:

• Botulism: A paralytic illness caused by a neurotoxin.

• Clostridium botulinum: An obligate anaerobe that produces botulinum toxin.

• Mouse bioassay: Used to detect the presence of toxin.

Step-by-Step Guidance

1. Identify the symptoms: cranial nerve paralysis, descending paralysis, respiratory failure.

2. Note the food source: canned chili, which can support anaerobic bacterial growth.

3. Interpret the lab findings: bacteria only grow in anaerobic conditions.

4. Recall which bacteria and disease fit this profile.

Try solving on your own before revealing the answer!